tdobkowski
Actually your website is loading settings from no cached files
You need to add your customizations in /templates/yourtemplate/css/ folder in a file named custom.css
you need to create one from scratch
After you completed your website customization then you can enable again css optimization in t3-asset folder
If you added your customizations before in css cached folder then i think you lost it and you should restart your customization from scratch -
In the documentation link i sent above you should look at the customization section - specifically to custom css
Regards